(1) Field of the Invention
This invention relates to a full-turn type working machine such as a hydraulic excavator and the like, and more particularly to a full-turn type working machine which can turn the upper rotary body even in a narrow working site to carry out excavation or other jobs.
(2) Description of the Prior Art
In Japanese Laid-Open Utility Model Specification Nos. 62-16150, 63-36567, 63-36568 and 63-100550, Applicant proposed full-turn type working machines which can turn the upper rotary body even in a narrow working site for excavation or other jobs.
Illustrated in FIGS. 1 and 2 is a small-size hydraulic excavator as an example of the prior art full-turn type working machine of this type.
In these figures, indicated at 1 is a lower travelling body, and at 2 is an upper rotary body which is swivellably mounted on the lower travelling body 1. The upper rotary body 2 is provided with a frame 2A which constitutes a skeletal structure together with a bracket 10 which will be described hereinafter. A machine room 3 is provided on the frame 2A on the right side of the bracket 10. As shown in FIG. 2, engine 4, radiator 5 and hydraulic pump 6 are provided in the machine room 3. The hydraulic pump 6 is driven from the engine 4 to supply operating oil in an oil tank 7 in a rear portion to a motor for driving the lower travelling body 1 and a motor for turning the upper rotary body 2 (both of the motors are not shown) and to cylinders 17A, 18A and 19A which will be described hereinafter. In FIG. 2, the top cover of the machine room 3 and working equipments 16, which will be described hereinafter, are removed for the convenience of illustration.
Denoted at 8 is an operator's cabin which is provided on the frame 2A in a front left portion of the upper rotary body 2, and which is equipped with an operator's seat 8A. A plural number of operating levers (not shown) are provided on the front side of the operator's seat 8A to switch the position of a control valve 11 which will be described hereinafter. The reference numeral 9 denotes a door which is provided on the left side of the operator's cabin 8 to open and close the opening through which the operator gets into and out of the operator's cabin 8. The door 9 is swingably attached to a rear left side portion of the operator's cabin 8 by means of hinges (not shown), and swung open rearward as shown in the drawing.
Indicated at 10 are a pair of brackets which are provided in the front center portion of the frame 2A between the machine room 3 and the operator's cabin 8 to form part of the main structure of the frame 2A. Pivotally mounted on these brackets 10 are a boom 17 and cylinder 17A of the working equipments 16. The reference numeral 11 denotes a control valve which is mounted on the frame 2A rearward of the brackets 10. This control valve 11 is switchable by way of the operating levers in the operator's cabin 8 to control the supply of the operating oil from the hydraulic pump 6 to the travelling and rotating motors and the respective cylinders 17A, 18A and 19A. Designated at 12 is a fuel tank which is mounted on the frame 2A side by side with the oil tank 7 and in a position rearward of the operator's cabin 8 and on the front side of a counterweight 13 which will be described hereinafter.
Denoted at 13 is the just-mentioned counterweight which is located in a rear center portion of the upper rotary body 2, and at 14 is a reinforcing member which is provided integrally on the rear side of the counterweight 13 and which is formed by arcuately bending a thick plate material of iron or the like along a circle 15 of a predetermined rotational radius R which will be explained hereinafter, the reinforcing member 14 covering the rear side of the machine room 3 to protect same against obstacles in the circumference. In this case, the corner portions A, B, C and D of the reinforcing member 14, machine room 3, operator's cabin 8 and the like are located to inscribe the circle 15 of the rotational radius R as shown in FIG. 2 to prevent the corner portions from hitting against obstacles on the outer side of the circle 15.
Further, the reference numeral 16 indicates the working equipments which are vertically swingable and which includes a boom 17 pivotally connected to the brackets 10 by pins and turned up and down by the boom cylinder 17A, an arm 18 pivotally connected to the fore end of the boom 17 by pin and swung by the arm cylinder 18A, and a bucket 19 pivotally connected to the fore end of the arm 18 by pin and swung by the bucket cylinder 19A to perform a ground excavating job or the like.
With the prior art hydraulic excavator of the above-described arrangement, earth excavation is carried out by turning the bucket 19 by the bucket cylinder 19A while swinging the boom 17 and arm 18 up and down by the boom cylinder 17A and the arm cylinder 18A, respectively. In a narrow working site, the boom 17 is turned upward (uplifted) and the arm 18 and bucket 19 are turned into folded state as shown in FIG. 1, and then the upper rotary body 2 is turned along the circle 15 with the rotational radius R shown in FIG. 2 thereby permitting to turn the boom 17 and arm 18 into a desired direction to excavate the ground with the bucket 19.
In case of the above-described prior art, when the door 9 of the operator's cabin 8 is opened as shown in FIG. 2, the outer free end of the door 9 is protruded on the outer side of the circle 15 of the rotational radius R. This is problematic especially in the summer season or on hot days when the operator often continues the excavation with the door 9 open to get wind into the cabin 8.
Namely, the prior art has a problem that, when the upper rotary body 2 is turned with the door 9 open, there are possibilities of the door 9 colliding against circumferential structures, resulting in damages of the door 9 or injury of the operator.